Brush steaks with 1 Tb of oil. Coat heavily with peppercorns and coriander seeds. Sprinkle with salt.

Heat remaining oil in skillet on high heat. Add steaks and cook 4 inutes one side; turn over and cook 4 minutes the other side. Turn again and cook 3 minutes more for medium rare, or until desired degree of doneness.

Remove from skillet and keep warm. Add port and reduce until 2 Tb remain. Add vinegar and stock; bring to boil and reduce by half. Remove from heat and whisk in butter. Place steaks on plate and coat with sauce.